org.apache.commons.lang
Class CharSet

java.lang.Object
  org.apache.commons.lang.CharSet

All Implemented Interfaces:

Serializable

public class CharSet

extends Object

implements Serializable

A set of characters.

Instances are immutable, but instances of subclasses may not be.

Since:

1.0

Version:

$Id: CharSet.java,v 1.20 2003/08/22 17:25:33 ggregory Exp $

Author:

Henri Yandell, Stephen Colebourne, Phil Steitz, Pete Gieser, Gary Gregory

See Also:

Serialized Form

Field Summary

static CharSet	ASCII_ALPHA A CharSet defining ASCII alphabetic characters "a-zA-Z".
static CharSet	ASCII_ALPHA_LOWER A CharSet defining ASCII alphabetic characters "a-z".
static CharSet	ASCII_ALPHA_UPPER A CharSet defining ASCII alphabetic characters "A-Z".
static CharSet	ASCII_NUMERIC A CharSet defining ASCII alphabetic characters "0-9".
protected static Map	COMMON A Map of the common cases used in the factory.
static CharSet	EMPTY A CharSet defining no characters.

Constructor Summary

protected	CharSet(String setStr) Constructs a new CharSet using the set syntax.
protected	CharSet(String[] set) Constructs a new CharSet using the set syntax.

Method Summary

protected void	add(String str) Add a set definition string to the CharSet.
boolean	contains(char ch) Does the CharSet contain the specified character ch.
boolean	equals(Object obj) Compares two CharSet objects, returning true if they represent exactly the same set of characters defined in the same way.
CharRange[]	getCharRanges() Gets the internal set as an array of CharRange objects.
static CharSet	getInstance(String setStr) Factory method to create a new CharSet using a special syntax.
int	hashCode() Gets a hashCode compatable with the equals method.
String	toString() Gets a string representation of the set.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

EMPTY

public static final CharSet EMPTY

A CharSet defining no characters.

Since:

2.0

ASCII_ALPHA

public static final CharSet ASCII_ALPHA

A CharSet defining ASCII alphabetic characters "a-zA-Z".

Since:

2.0

ASCII_ALPHA_LOWER

public static final CharSet ASCII_ALPHA_LOWER

A CharSet defining ASCII alphabetic characters "a-z".

Since:

2.0

ASCII_ALPHA_UPPER

public static final CharSet ASCII_ALPHA_UPPER

A CharSet defining ASCII alphabetic characters "A-Z".

Since:

2.0

ASCII_NUMERIC

public static final CharSet ASCII_NUMERIC

A CharSet defining ASCII alphabetic characters "0-9".

Since:

2.0

COMMON

protected static final Map COMMON

A Map of the common cases used in the factory. Subclasses can add more common patterns if desired.

Since:

2.0

Constructor Detail

CharSet

protected CharSet(String setStr)

Constructs a new CharSet using the set syntax.

Parameters:

setStr - the String describing the set, may be null

Since:

2.0

CharSet

protected CharSet(String[] set)

Constructs a new CharSet using the set syntax. Each string is merged in with the set.

Parameters:

set - Strings to merge into the initial set

Throws:

NullPointerException - if set is null

Method Detail

getInstance

public static CharSet getInstance(String setStr)

Factory method to create a new CharSet using a special syntax.

• null or empty string ("") - set containing no characters
• Single character, such as "a" - set containing just that character
• Multi character, such as "a-e" - set containing characters from one character to the other
• Negated, such as "^a" or "^a-e" - set containing all characters except those defined
• Combinations, such as "abe-g" - set containing all the characters from the individual sets

The matching order is:

1. Negated multi character range, such as "^a-e"
2. Ordinary multi character range, such as "a-e"
3. Negated single character, such as "^a"
4. Ordinary single character, such as "a"

Matching works left to right. Once a match is found the search starts again from the next character.

If the same range is defined twice using the same syntax, only one range will be kept. Thus, "a-ca-c" creates only one range of "a-c".

If the start and end of a range are in the wrong order, they are reversed. Thus "a-e" is the same as "e-a". As a result, "a-ee-a" would create only one range, as the "a-e" and "e-a" are the same.

The set of characters represented is the union of the specified ranges.

All CharSet objects returned by this method will be immutable.

Parameters:

setStr - the String describing the set, may be null

Returns:

a CharSet instance

Since:

2.0

add

protected void add(String str)

Add a set definition string to the CharSet.

Parameters:

str - set definition string

getCharRanges

public CharRange[] getCharRanges()

Gets the internal set as an array of CharRange objects.

Returns:

an array of immutable CharRange objects

Since:

2.0

contains

public boolean contains(char ch)

Does the CharSet contain the specified character ch.

Parameters:

ch - the character to check for

Returns:

true if the set contains the characters

equals

public boolean equals(Object obj)

Compares two CharSet objects, returning true if they represent exactly the same set of characters defined in the same way.

The two sets abc and a-c are not equal according to this method.

Parameters:

obj - the object to compare to

Returns:

true if equal

Since:

2.0

hashCode

public int hashCode()

Gets a hashCode compatable with the equals method.

Returns:

a suitable hashCode

Since:

2.0

toString

public String toString()

Gets a string representation of the set.

Returns:

string representation of the set